Inductance



L. F. BIRD lNqucTANcE.

Fl LED JAN.

' l I I l tll 0 M MW i atentecl Dec. 26, 1922.

UNITED STATES PATENT OFFICE.

LESTER F. BIRD, OF SEATTLE, WASHINGTON.

IND UCTANCE.

Application filed January 5, 1921.

" "my; concern Be it known that I, IJISTEIZ citizen ot the lnited- States.

tion. inductanccs.

which the cllowing is a sp TlllF-l inve n relates to An object or too invention to provide a simple and compact arrangement ct inducance coils for interconnected circi ts and including coil in inductive relation w'h one another whereby the inductance of suh circuits is varied and the ratio of trans formation also varied as sod.

h ly invention is app :able to othe .ot'uis of electrical iuductan.

for the pr Y ose of varying the total inductance of any circuit and the ref transformation.

Further features and objects of the invention will be m re fully understood from the following d. led description and the con'ipanylng drawings, in which- F 1 is a side elevation of an embodi ment of the invention applicable for radio sets; and

duced scale, of

The form 2 a diagram, on a somewhat rethe same. 01? the invention illustrated in is particularly adapted for a g set in which the outer coil 1. is the antenna coil, the ncrmost coil it connected to the plate or the vacuum tube oscillator and the upper coil 3 is connected to the grid of the vacuum tube oscillator. The coil 1 is formed 01'? the required niunber of turns of the desired wire and wound on a suitable insulating base whose inner, cylindrical base makes a snug friction fit with the outer face of coil 2. In Fig. 2 I have indicated diagrammatically the windings 21, of the antenna coil 1 and the hollow or tubular base 5 of insulating material on which. the windings 4, are mounted.

The direction of winding of the windings 4 may be counterclockwise as viewed from above.

The coil 2 comprises the dicated at 6 in is similarly constructed and desired number oi turns 1n- F 1g. 2, and mounted on a SAP Serial No. 435,271.

suitable base 7 of insulating material. Such coil (3 may be wound in counter clockwise direction, as viewed. from above.

Coil 3 is wound similarly of suitable windings 8 mounted on a suitable base 9 of insulating material. The insulating bases '4", 9, may be separate from one another and secured together, or the bases 7, 9, may be integral and formed of the different di anioters as indicated.

Preferably. the winding with the winding 6.

is continuous Upon slipping the coil 1 relatively to the coil 2, in either dire tion parallel to the longitudinal axis of the cylindrical b i the windin relative to the winding 6 is varied and similarly the inductive relation of the winding 4 relative to the winding 8 is separately 'variec. iI invention is particularly applicable ng sets, since, as I have arrangement of the inducgrid and plate of the vacuum tube oscillator and the coil for the antenna mounted about the plate coil renders the output of the oscillations substantially constant notwithstanding that the wave length may be varied.

It will be noted that the invention providcs :t'or a compact moi'inting for the several ind: permits of ready adjustin radio transmits llSCOVQI'Qd, such tances for the i stances and inent oi; the inductauces to one another.

lVheroas I have described my invention by reference to specific forms thereof. it will e understood 2.1211; many changes and modifications may be made without depm-ting from the spirit of the invention, as defined by the appended claim.

claim,

In a radio set, an antenna coil, a hollow insulating base supporting said antenna coil, a plate coil disposed within said hollow base, a cylindrical base supporting said plate coil, said hollow base being frictionally held on said plate coil, a grid coil, and an insulating base for said grid coil said grid coil base having a fixed relation to said cylindrical base.

In testimony whereof I have afiixed my signature.

LESTER F. BIRD.

4e '7, the inductive relation of 

